Scale Out Architecture

Is there any best practice how to deploy a multi-node BW on HANA system?

There is very good summary of scale out best practices in SCN put together by SAP's CSA expert group.

http://scn.sap.com/docs/DOC-39682

Is there a recommendation from SAP what node size works best for a BWoH scale-out system?

Please have a look to OSS note 1855041.

http://service.sap.com/sap/support/notes/1855041

Is there a way to automatically redistribute and partition data in a BW on HANA scale-out environment?

There is a automatic partitioning available for scale-out landscapes described in SAP Note 1908075. This can improve BW query performance. Please make sure to review OSS note 2019973 which explains in detail all best practices around dealing with large data volume tables!

http://scn.sap.com/community/hana-in-memory/blog/2013/09/03/sap-hana-landscape-redistribution-with-sp6

http://service.sap.com/sap/support/notes/1908075

http://service.sap.com/sap/support/notes/2019973

There is also a How-To paper about configuring SAP HANA Table-Distribution for BW-on-HANA Scale-Out Systems.

https://scn.sap.com/docs/DOC-57368